(a) Field of the Invention
The present invention relates to a display device and a driving method thereof and, more particularly, to a display device and driving method thereof having increased luminance and decreased power consumption.
(b) Description of the Related Art
In general, a liquid crystal display (“LCD”) includes a first display panel having pixel electrodes and second display panel having a common electrode, and a liquid crystal layer having an anisotropic dielectric material disposed therebetween. The pixel electrodes are arranged in a substantially matrix pattern, and are connected to switching elements such as thin film transistors (“TFTs”), for example, to sequentially receive data voltages. The common electrode is formed on the entire surface of the second display panel and may receive a common voltage. A liquid crystal capacitor is formed from each pixel electrode, the common electrode and the liquid crystal layer therebetween. The liquid crystal capacitor and the switching element connected to the liquid crystal capacitor form a pixel unit.
In the LCD, a voltage is applied to the pixel electrodes and the common electrode to form an electric field therebetween, e.g., in the liquid crystal layer. The strength of the electric field determines the transmittance of light passing through the liquid crystal layer, and is controlled by the voltage applied to the pixel electrodes and the common electrode to display a desired image. When an electric field is applied to the liquid crystal layer in only one direction, e.g. polarity, degradation of the LCD may occur. In order to prevent the degradation, a polarity of the data voltage with respect to a polarity of the common voltage may be inverted for each frame, row or pixel, for example.
However, a range of the data voltage used for displaying an image using row inversion, e.g., an inversion method in which the polarity of the data voltage is inverted by rows of pixels, is smaller than a range of the data voltage used for displaying an image using dot inversion, e.g., an inversion method in which the polarity of the data voltage is inverted by individual pixels. Thus, if a threshold voltage for driving liquid crystals in the liquid crystal layer is high, such as in a vertical alignment (“VA”) mode LCD, a lower voltage of a data voltage range for gray voltage representation used for image display becomes as low as the threshold voltage. Thus, accurate luminance representation becomes difficult.
In addition, small LCDs, such as those used in mobile phones, for example, perform row inversion, which inverts the polarity of the data voltage by rows of pixels to reduce power consumption, but because the small LCDs can require high resolution, power consumption is thereby increased.